Always. Always. Quality over quantity.
The only product that should (and needs) to be cut is [raw]fentanyl - or some other extremely powerful opiate or tranquilizer. Any substance in which the raw product would potentially kill the average consumer.
You are really only cheating yourself by trying to make extra money. OK you make an extra $20 off some sales and/or stretch each gram a tenth or two. It isn't going to last long, and if it does, you're probably taking advantage of someone who is desperate, and that will build resentment - the type you don't see coming. As soon as the next guy who comes along with some better stuff, he's gonna take your business. If this happens you better hope your rival misses a shipment and the customer doesn't want to wait. That way you can get another play to give them some raw product and build your reputation and clientelle back.
Speaking from experience, usually an addict is pretty loyal to their best dealer, they want to try to keep them safe and secret so nothing bad happens to them. When shit hits the fan, people are probably more likely to give up their back up dealer with the garbage product before the good one - either to snitch on, to rip off ..whatever. The guy with shitty product probably is not the first one invited to the party... "Yea, hey everybody, this is the guy with the amphetamine that barely does anything and tastes like acetaminophen." .. They're gonna say, "call the other guy... I'd rather pay the extra $20."
o7